Grating configurations for optical beam steering

Abstract

An apparatus comprises: at least one optical source port providing an optical wave having a tunable spectral peak wavelength; one or more transmitting optical phased arrays (OPAs), each: coupled to the optical source port, wherein the OPAs form beams with a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a perpendicular plane; and receiving OPAs, each: coupled to a coherent receiver and configured to receive optical waves characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within the perpendicular plane. At least two beams' wavelength-controlled angular tuning ranges are at least partially non-overlapping, and each of the receiving OPAs' wavelength-controlled angular tuning ranges at least one partially overlaps with at least one of the wavelength-controlled angular tuning ranges of the beams.

What is claimed is: 
     
         1 . An apparatus comprising:
 at least one optical source port providing an optical wave having a spectral peak wavelength that is tunable;   one or more transmitting optical phased arrays (OPAs), each transmitting OPA of the one or more transmitting OPAs:
 being coupled to the optical source port, and 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, 
 wherein the one or more transmitting OPAs are configured to form a plurality of beams each characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; 
   wherein at least two of the wavelength-controlled angular tuning ranges of the plurality of beams are at least partially non-overlapping, and each of the wavelength-controlled angular tuning ranges of the plurality of receiving OPAs at least partially overlaps with at least one of the wavelength-controlled angular tuning ranges of the plurality of beams.   
     
     
         2 . The apparatus of  claim 1 , wherein the one or more transmitting OPAs comprise a plurality of transmitting OPAs, and each transmitting OPA of the plurality of transmitting OPAs is configured to form a different one of the plurality of beams. 
     
     
         3 . The apparatus of  claim 1 , wherein at least one of the one or more transmitting OPAs comprises:
 at least one waveguide configured to guide an optical wave along a propagation axis;   a plurality of sets of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide to emit a plurality of beams at different respective angles about an axis that is perpendicular to the propagation axis, the plurality of sets of grating elements comprising:
 a first set of grating elements with adjacent grating elements separated from each other along the propagation axis by a first length, and 
 a second set of grating elements with adjacent grating elements separated from each other along the propagation axis by the first length, where the second set of grating elements is separated from the first set of grating elements along the propagation axis by a gap without any grating elements at least twice as large as the first length. 
   
     
     
         4 . The apparatus of  claim 3 , wherein each grating element of the plurality of sets of grating elements is in contact with a strip of material having substantially the same index of refraction as the grating elements. 
     
     
         5 . The apparatus of  claim 3 , wherein the one or more transmitting OPAs consist of a single transmitting OPA configured to form the plurality of beams. 
     
     
         6 . The apparatus of  claim 3 , wherein each grating element of the plurality of sets of grating elements extends along a direction substantially perpendicular to the propagation axis. 
     
     
         7 . The apparatus of  claim 3 , wherein each grating element of the plurality of sets of grating elements comprises:
 a first portion positioned to perturb a first portion of a wavefront of the optical wave at a first location along the propagation axis, and   a second portion positioned to perturb a second portion of the wavefront at a second location along the propagation axis different from the first location, where the second portion of the wavefront is at least partially non-overlapping with the first portion of the wavefront.   
     
     
         8 . A method for managing optical phased array beam steering, the method comprising:
 providing, from at least one optical source port, an optical wave having a spectral peak wavelength that is tunable;   transmitting a plurality of beams from one or more transmitting optical phased arrays (OPAs), each transmitting OPA of the one or more transmitting OPAs:
 being coupled to the optical source port, and 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, 
 wherein the one or more transmitting OPAs are configured to form the plurality of beams each characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   receiving optical waves into a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; 
   wherein at least two of the wavelength-controlled angular tuning ranges of the plurality of beams are at least partially non-overlapping, and each of the wavelength-controlled angular tuning ranges of the plurality of receiving OPAs at least partially overlaps with at least one of the wavelength-controlled angular tuning ranges of the plurality of beams.   
     
     
         9 . An apparatus comprising:
 at least one waveguide configured to guide an optical wave along a propagation axis; and   a plurality of sets of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide to emit a plurality of beams at different respective angles about an axis that is perpendicular to the propagation axis, the plurality of sets of grating elements comprising:
 a first set of grating elements with adjacent grating elements separated from each other along the propagation axis by a first length, and 
 a second set of grating elements with adjacent grating elements separated from each other along the propagation axis by the first length, where the second set of grating elements is separated from the first set of grating elements along the propagation axis by a gap without any grating elements at least twice as large as the first length. 
   
     
     
         10 . The apparatus of  claim 9 , further comprising:
 at least one optical source port providing an optical wave having a spectral peak wavelength that is tunable;   a transmitting optical phased array (OPA):
 being coupled to the optical source port, and 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, each of the optical grating antennas comprising a structure substantially identical to the waveguide and the plurality of sets of grating elements, and 
 being configured to form a plurality of beams each characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane. 
   
     
     
         11 . The apparatus of  claim 10 , wherein at least two of the wavelength-controlled angular tuning ranges of the plurality of beams are at least partially non-overlapping, and each of the wavelength-controlled angular tuning ranges of the plurality of receiving OPAs at least partially overlaps with at least one of the wavelength-controlled angular tuning ranges of the plurality of beams. 
     
     
         12 . The apparatus of  claim 9 , wherein each grating element of the plurality of sets of grating elements is in contact with a strip of material having substantially the same index of refraction as the grating elements. 
     
     
         13 . The apparatus of  claim 9 , wherein each grating element of the plurality of sets of grating elements comprises:
 a first portion positioned to perturb a first portion of a wavefront of the optical wave at a first location along the propagation axis, and   a second portion positioned to perturb a second portion of the wavefront at a second location along the propagation axis different from the first location, where the second portion of the wavefront is at least partially non-overlapping with the first portion of the wavefront.   
     
     
         14 . A method for fabricating an optical device, the method comprising:
 forming at least one waveguide configured to guide an optical wave along a propagation axis; and   forming a plurality of sets of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide to emit a plurality of beams at different respective angles about an axis that is perpendicular to the propagation axis, the plurality of sets of grating elements comprising:
 a first set of grating elements with adjacent grating elements separated from each other along the propagation axis by a first length, and 
 a second set of grating elements with adjacent grating elements separated from each other along the propagation axis by the first length, where the second set of grating elements is separated from the first set of grating elements along the propagation axis by a gap without any grating elements at least twice as large as the first length. 
   
     
     
         15 . An apparatus comprising:
 at least one waveguide configured to guide an optical wave along a propagation axis; and   a plurality of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide, each of the plurality of grating elements comprising:
 a first portion positioned to perturb a first portion of a wavefront of the optical wave at a first location along the propagation axis, and 
 a second portion positioned to perturb a second portion of the wavefront at a second location along the propagation axis different from the first location, where the second portion of the wavefront is at least partially non-overlapping with the first portion of the wavefront. 
   
     
     
         16 . The apparatus of  claim 15 , wherein each of the plurality of grating elements comprises:
 the first portion in contact with the waveguide at the first location and extending along a direction substantially perpendicular to the propagation axis, and   the second portion in contact with the waveguide at the second location and extending along a direction substantially perpendicular to the propagation axis.   
     
     
         17 . The apparatus of  claim 16 , wherein the first portion and the second portion of a particular grating element are connected to each other. 
     
     
         18 . The apparatus of  claim 15 , wherein the first portion and the second portion of a particular grating element are connected to each other. 
     
     
         19 . The apparatus of  claim 18 , wherein each of the plurality of grating elements comprises:
 the first portion in contact with the waveguide at a third location and extending to at least the first location, and   the second portion in contact with the waveguide at the third location and extending to at least the second location.   
     
     
         20 . The apparatus of  claim 18 , wherein the particular grating element extends along a substantially straight line that is at an angle that is not perpendicular to the propagation axis. 
     
     
         21 . The apparatus of  claim 15 , further comprising:
 at least one optical source port providing an optical wave having a spectral peak wavelength that is tunable;   a plurality transmitting optical phased arrays (OPAs), each transmitting OPA of the plurality of transmitting OPAs:
 being coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, each of the optical grating antennas comprising a structure substantially identical to the waveguide and the plurality grating elements, and 
 being configured to form a beam characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, each of the optical grating antennas comprising a structure substantially identical to the waveguide and the plurality grating elements, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane. 
   
     
     
         22 . The apparatus of  claim 21 , wherein
 at least two of the wavelength-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a wavelength-controlled angular tuning range that at least partially overlaps with a wavelength-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs, or   at least two of the phase-shift-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a phase-shift-controlled angular tuning range that at least partially overlaps with a phase-shift-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs.   
     
     
         23 . A method for fabricating an optical device, the method comprising:
 forming at least one waveguide configured to guide an optical wave along a propagation axis; and   forming a plurality of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide, each of the plurality of grating elements comprising:
 a first portion positioned to perturb a first portion of a wavefront of the optical wave at a first location along the propagation axis, and 
 a second portion positioned to perturb a second portion of the wavefront at a second location along the propagation axis different from the first location, where the second portion of the wavefront is at least partially non-overlapping with the first portion of the wavefront. 
   
     
     
         24 . An apparatus comprising:
 at least one optical source port providing an optical wave having a spectral peak wavelength that is tunable;   a plurality transmitting optical phased arrays (OPAs), each transmitting OPA of the plurality of transmitting OPAs:
 being coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to form a beam characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; 
   wherein at least two of the wavelength-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a wavelength-controlled angular tuning range that at least partially overlaps with a wavelength-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs, or at least two of the phase-shift-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a phase-shift-controlled angular tuning range that at least partially overlaps with a phase-shift-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs.   
     
     
         25 . The apparatus of  claim 24 , wherein at least two of the wavelength-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a wavelength-controlled angular tuning range that at least partially overlaps with a wavelength-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs. 
     
     
         26 . The apparatus of  claim 24 , wherein at least two of the phase-shift-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a phase-shift-controlled angular tuning range that at least partially overlaps with a phase-shift-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs. 
     
     
         27 . The apparatus of  claim 24 , wherein at least two of the wavelength-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a wavelength-controlled angular tuning range that at least partially overlaps with a wavelength-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs, and at least two of the phase-shift-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a phase-shift-controlled angular tuning range that at least partially overlaps with a phase-shift-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs. 
     
     
         28 . The apparatus of  claim 24 , wherein at least one of the plurality of transmitting OPAs comprises:
 at least one waveguide configured to guide an optical wave along a propagation axis;   a plurality of sets of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide to emit   a plurality of beams at different respective angles about an axis that is perpendicular to the propagation axis, the plurality of sets of grating elements comprising:
 a first set of grating elements with adjacent grating elements separated from each other along the propagation axis by a first length, and 
 a second set of grating elements with adjacent grating elements separated from each other along the propagation axis by the first length, where the second set of grating elements is separated from the first set of grating elements along the propagation axis by a gap without any grating elements at least twice as large as the first length. 
   
     
     
         29 . The apparatus of  claim 28 , wherein each grating element of the plurality of sets of grating elements is in contact with a strip of material having substantially the same index of refraction as the grating elements. 
     
     
         30 . The apparatus of  claim 24 , wherein at least one of the plurality of transmitting OPAs comprises:
 at least one waveguide configured to guide an optical wave along a propagation axis;   a plurality of grating elements distributed along the waveguide and configured to perturb a portion of the optical wave as it propagates along the waveguide to emit a plurality of beams at different respective angles about an axis that is perpendicular to the propagation axis, the plurality of grating elements comprising:
 a first portion positioned to perturb a first portion of a wavefront of the optical wave at a first location along the propagation axis, and 
 a second portion positioned to perturb a second portion of the wavefront at a second location along the propagation axis different from the first location, where the second portion of the wavefront is at least partially non-overlapping with the first portion of the wavefront. 
   
     
     
         31 . The apparatus of  claim 30 , wherein the first and the second portion of a particular grating element are connected to each other. 
     
     
         32 . A method for managing optical phased array beam steering, the method comprising:
 providing, from at least one optical source port, an optical wave having a spectral peak wavelength that is tunable;   transmitting beams from a plurality transmitting optical phased arrays (OPAs), each transmitting OPA of the plurality of transmitting OPAs:
 being coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to form a beam characterized by a wavelength-controlled angular tuning range within a first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; and 
   receiving optical waves into a plurality of receiving OPAs, each receiving OPA of the plurality of receiving OPAs:
 being coupled to a coherent receiver that is coupled to the optical source port, 
 comprising a plurality of optical phase shifters that are tunable, and a plurality of optical grating antennas, including two or more optical grating antennas each coupled to a different respective one of the optical phase shifters, and 
 being configured to receive optical waves from a set of receiving angles characterized by a wavelength-controlled angular tuning range within the first plane and a phase-shift-controlled angular tuning range within a plane perpendicular to the first plane; 
   wherein at least two of the wavelength-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a wavelength-controlled angular tuning range that at least partially overlaps with a wavelength-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs, or at least two of the phase-shift-controlled angular tuning ranges of the beams of the plurality of transmitting OPAs are at least partially non-overlapping and each of plurality of receiving OPAs has a phase-shift-controlled angular tuning range that at least partially overlaps with a phase-shift-controlled angular tuning range of at least one of the beams of the plurality of transmitting OPAs.